I had a look at Appendix L Chapter IV 4 c) International Sporting Code for this and last year, it used to be:
Except in cases of force majeure (accepted as such by the Stewards), any line painted on the track at the pit exit for the purpose of separating cars leaving the pits from those on the track must not be crossed by any part of a car leaving the pits.
This changed to:
Except in cases of force majeure (accepted as such by the Stewards), any tyre of a car exiting the pit lane must not cross any line painted on the track at the pit exit for the purpose of separating cars leaving the pit lane from those on the track.
The sentence order was changed but the key difference is the change from 'any part of the car' to 'any tyre of the car' - IMHO this was done because the only car part that was actually looked at to enforce this was the tyres.
Hypothetically this would have been 'any part of the car' crossing the line but it would have been fine as they only ever looked at the tyres.
The change of the wording was probably supposed to reflect that - i personally do not believe it was ever meant to change the meaning or intention of the rule.
AFAIK this used to be fine:
This was a breach of the rule:
(correct me if i'm wrong on that)
From LEC's onboard and the wording in the decision document ("All parties agreed that Car 1 did have part of its front left and rear left tyre on the left side of the yellow line.") it looked like this was roughly what Max did:
But since yesterday the rule essentially says that this is perfectly fine:
As the decision document made it precedent:
In this case, the car did not “cross” the line – to do so it would have needed to have a full wheel to the left of the yellow line.
I find it very hard to believe this is consistent with the intent of the rule which has "the purpose of separating cars leaving the pits from those on the track" and to me it seems that it's another case of the stewards (mis)interpreting the rules post race to not have to interfere with the result.
With the complete lack of penalizing drivers who ignored blue flags, ignoring the pre race times for having wheels on the car, delaying the race and thus screwing over those who actually had a look at the rain radar (M, AM, McL), alleged disagreements about those delays and the pit exit line saga race direction really didn't look all too great, one could argue that there really isn't any improvement from last year - but hey, at least the drivers wear the proper underwear.